1: The Potential Benefit of Esophageal Sparing During Palliative Radiotherapy for Lung Cancer
Bibliographic record
Abstract
Purpose: A 2007 meta-analysis of several randomized controlled trials assessing optimal doses for palliative lung radiation concluded that radiation doses of 35 Gy10 or greater improved overall survival at one and two years compared to lower doses at the cost of an increased toxicity related to esophagitis.Esophageal sparing has been proposed as a mechanism of reducing this toxicity.A planning study was initiated to assess the potential impact of esophageal-sparing IMRT (ES-IMRT) for palliative lung radiotherapy, compared to the current standard of care using parallel-opposed pair beams (POP). Methods and Materials:In this institutional research ethics board-approved study, patients with lung cancer treated to a dose of 30 Gy in 10 fractions between August 2015 and January 2016 were identified.Additional inclusion criteria required the D50 to contain at least 5 cm of esophagus.The radiation treatment plans were optimized using ES-IMRT by limiting the max esophageal point dose to 80% of the prescription.This was achieved by creating a 5 mm ring around the esophagus.If any portion of the GTV was within this ring, the coverage was compromised such that a point dose could receive as low as 80% of the intended prescription.Both the clinical POP and optimized ES-IMRT plans were evaluated for the likelihood of esophagitis (≥ Grade 2) and pneumonitis (≥ Grade 2), using published Lyman-Kutcher-Burman normal tissue complication probabilities (LKB-NTCP) models.The input parameters for the LKB models were D50 = 44.9,n = 0.34, m = 0.34 and D50 = 29.9,n = 1, m = 0.41 for esophagitis and pneumonitis, respectively.The mean normalized total dose (NTD mean) of the PTV, and the mean dose to the esophagus (esophageal mean) and lung (lung mean) were determined.Results: A total of 13 patients met our inclusion criteria and were analyzed, of which 11/13 had the GTV directly abutting the esophagus.The median [range] of the GTV and PTV were 90.6 cc [22.3 -199.8] and 321.8 cc [164.1 -564.9],respectively.Using ES-IMRT, the median esophageal mean and lung mean dose reduced from 17.0 and 7.9 Gy to 6.8 and 7.7 Gy, respectively.Using the LKB model, the theoretical probability of symptomatic esophagitis and pneumonitis reduced from 13 to 1%, and from 5 to 3%, respectively.The median clinical POP NTDmean was 32.8 Gy, while the median ES-IMRT NTDmean was 33.2 Gy.Conclusions: Advanced radiotherapy techniques such as ES-IMRT may have clinical utility in reducing treatment-related toxicity in advanced lung cancer patients.Our data suggests that the rate of esophagitis can be reduced from 13 to 1%, without compromising tumour control.The results of this planning study will inform the design of a Phase II randomized controlled trial, Palliative Radiation of Advanced Central lung Tumours with Intentional Avoidance of the Esophagus (PROACTIVE).
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.013 | 0.002 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".